Background: The discovery of nitric oxide as mediator in cardiac postoperative vasoplegia encourages the use of inhibitory drugs such as methylene blue. This drug has been used with favorable results in isolated cases. The purpose of this article is to analyze the incidence of the postoperative vasoplegic syndrome, to consider its prognosis, and to evaluate the effect of intravenous methylene blue on mortality.
Methods: Cardiac surgery patients were consecutively included. Vasoplegic syndrome was defined by the presence of the following five criteria: (1) hypotension, (2) low filling pressures, (3) high or normal cardiac index, (4) low peripheral resistance, and (5) vasopressor requirements. Those with vasoplegia were randomized to receive 1.5 mg/Kg of methylene blue or a placebo. A p value less than 0.05 was considered significant.
Results: Six hundred thirty eight cardiac surgery patients were consecutively included in this study. Fifty-six of these patients fulfilled vasoplegia criteria (8.8%) resulting in higher mortality (10.7% or 6 of 56 patients vs 3.6% or 21 of 582 patients; p value = 0.02). Those treated with methylene blue showed morbidity and mortality reductions (0% versus 21.4% or 6 of 28 patients; p value = 0.01). The duration of the vasoplegic syndrome was shorter in those patients treated with the drug, lasting less than 6 hours in all patients. Patients in the control group showed a slower recovery, lasting more than 48 hours in 8 patients (p value = 0.0007).
Conclusions: Vasoplegic postoperative syndrome was seen in 8.8% of all patients. Outcome in patients with vasoplegia was worse with increased morbidity and mortality. The use of methylene blue reduced the high mortality in this population.